A new lens on biodiversity
South Africa is celebrated as one of the world’s most biodiverse countries – home to unique plants, animals, and ecosystems found nowhere else on Earth. But while we often speak about protecting species and ecosystems, there is a quieter, less visible layer of biodiversity that is just as important: genetic diversity.
Genetic diversity is the variation found within species – the differences in DNA that help plants, animals, and other organisms survive, reproduce, and adapt to change. Without this hidden reservoir of diversity, species lose the ability to cope with new challenges such as climate change, diseases, habitat loss, or pollution.
What the NBA 2025 reveals
In National Biodiversity Assessment (NBA) 2025 (being launched on 9 December 2025), South Africa has assessed genetic health at a national scale using two international indicators adopted under the Kunming-Montreal Global Biodiversity Framework. These indicators help us understand whether populations are large, connected, and genetically robust enough to survive into the future.
The initial findings show concerning signs of genetic decline, but also opportunities for action and recovery.
- Many species have populations that are too small to maintain long-term genetic health
The first indicator, known as the Ne 500 indicator, measures the proportion of populations with an effective population size (Ne) above 500. This number represents how many individuals in a population are actually contributing genetically to the next generation. Populations with an Ne above 500 are generally stable enough to maintain genetic diversity. Below this threshold, genetic diversity erodes over time, increasing the risk of inbreeding and extinction.
South Africa’s initial assessment covering species across different ecosystems resulted in an Ne 500 score of 0.42. This means 58% of measured populations are below the safe threshold, signalling that genetic erosion is already underway.
Importantly, even some Least Concern and Near Threatened species showed weak genetic indicators, suggesting genetic decline is often invisible until it becomes a serious problem.
The population of the Near Threatened southern white rhinoceros (Ceratotherium simum simum) numbers over 14 000 individuals, yet genetic studies reveal its effective population size (Ne) is under 100 – well below the Ne 500 threshold, reflecting serious genetic erosion from the historically small recovery population. Poaching still impacts this species (see key message A6). © Greg Martindale.
- Most populations still exist – and that gives us room to act
The second indicator, called the Populations Maintained or PM indicator, measures how many populations of a species are still present on the landscape. South Africa scored 0.95, meaning most populations remain intact.
This is a critical positive finding: although genetic diversity is declining, the opportunity to recover it still exists. If populations are conserved, connected, and managed well, they can regain genetic strength, supporting long-term survival.
Why genetic diversity matters
Genetic diversity affects everything from how well a species can reproduce to how it adapts to changing climate conditions. Low genetic diversity heightens extinction risk, especially when combined with other pressures such as habitat loss and fragmentation, climate change, unsustainable harvesting, or poorly planned translocations.
Protecting genetic diversity allows species to keep evolving – ensuring they remain resilient in the face of environmental change.
What South Africa needs to do next
The NBA 2025 makes one point clear: genetics must become a central part of conservation planning.
Several steps are already underway:
- Expanding assessments across full taxonomic groups: To get a complete picture of the nation’s genetic health, more species especially those not yet studied will need to be assessed using standardised methods.
- Investing in genetic monitoring: Monitoring species’ genetic diversity at different points in time will reveal whether conservation actions are working, and where interventions are urgently needed.
- Using new genetic indicators for planning and protection: Tools such as the EDGE Index (evolutionarily distinct, globally endangered) and the Expected Loss of Phylogenetic Diversity Indicator help highlight species whose loss would erase large branches of evolutionary history.
- Integrating genetic richness into national planning: Environmental impact assessments, protected area expansion, systematic biodiversity planning, and the identification of Key Biodiversity Areas should incorporate genetic data or reliable proxies to ensure that conservation priorities reflect not just where species occur, but how genetically healthy they are.
A hopeful path forward
Although South Africa’s first national genetic assessment shows that many species are losing genetic diversity, it also reveals that most populations still exist and can be recovered. With coordinated action, improved monitoring, and the integration of genetic information into conservation programmes, South Africa can safeguard the evolutionary future of its rich biodiversity.
Genetic diversity is a new and powerful lens for understanding nature — one that offers exciting possibilities for research, innovation, and policy. By using it wisely, we can strengthen the resilience of our ecosystems and ensure that South Africa’s natural heritage thrives for generations to come.
From 9 December 2025, you will be able to explore the full NBA 2025 results and dive deeper into South Africa’s biodiversity.
Visit: http://nba.sanbi.org.za/